ON THE CHIRALITY OF POLYVINYL COMPOUNDS .17. INVESTIGATIONS ON MAIN-CHAIN CHIRAL COPOLYMERS WITH ALTERNATING STRUCTURE

3,4-O-Cyclohexylidene-D-mannitol 1,2:5,6-bis-O-[(4-vinylphenyl)boronat e] (M1) was copolymerized with methyl methacrylate (MMA) in presence o f AlEt1,5Cl1,5 or SnCl4. The expected alternating bis(4-vinylphenylbor onic acid)-MMA triad structures were only formed to a lesser extent. I nstead, predominantly alternating 4-vinylphenylboronic acid-MMA struct ures were obtained. Since no crosslinking was observed, a cyclocopolym erization must have occurred. In this case an MMA unit is inserted bet ween the two styrene residues of M1, thus forming a 21-membered ring s ystem. Copolymerization forming alternating 4-vinylphenylboronic acid- MMA diads is apparently even faster than the direct cyclopolymerizatio n forming distryryl diads. After removal of the template (3,4-O-cycloh exylidene-D-mannitol), these copolymers still show pronounced optical activity and circular dichroism with a negative Cotton effect at 233 n m. After deboronation of the copolymers, optically active, predominant ly alternating styrene-MMA copolymers are obtained.